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  <title>预定义常量</title>

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</div><hr /><div id="password.constants" class="appendix">
 <h1>预定义常量</h1>

 <p class="simpara">
下列常量作为 PHP 核心的一部分总是可用的。
</p>

 <p class="para">
  <dl>

   
    <dt id="constant.password-bcrypt">
     <strong><code>PASSWORD_BCRYPT</code></strong>
     (<span class="type"><a href="language.types.integer.html" class="type integer">integer</a></span>)
    </dt>

    <dd>

     <p class="para">
      <strong><code>PASSWORD_BCRYPT</code></strong> is used to create new password
      hashes using the <strong><code>CRYPT_BLOWFISH</code></strong> algorithm.
     </p>
     <p class="para">
      This will always result in a hash using the &quot;$2y$&quot; crypt format, 
      which is always 60 characters wide.
     </p>
     <p class="para">
      Supported Options:
     </p>
     <ul class="itemizedlist">
      <li class="listitem">
       <p class="para">
        <em>salt</em> - to manually provide a salt to use when hashing the password.
        Note that this will override and prevent a salt from being automatically generated.
       </p>
       <p class="para">
        If omitted, a random salt will be generated by <span class="function"><a href="function.password-hash.html" class="function">password_hash()</a></span> for
        each password hashed. This is the intended mode of operation.
       </p>
      </li>
      <li class="listitem">
       <p class="para">
        <em>cost</em> - which denotes the algorithmic cost that should be used. 
        Examples of these values can be found on the <span class="function"><a href="function.crypt.html" class="function">crypt()</a></span> page.
       </p>
       <p class="para">
        If ommitted, a default value of <em>10</em> will be used. This is a good
        baseline cost, but you may want to consider increasing it depending on your hardware.
       </p>
      </li>
     </ul>
    </dd>

   
   
    <dt id="constant.password-default">
     <strong><code>PASSWORD_DEFAULT</code></strong>
     (<span class="type"><a href="language.types.integer.html" class="type integer">integer</a></span>)
    </dt>

    <dd>

     <p class="para">
      The default algorithm to use for hashing if no algorithm is provided.
      This may change in newer PHP releases when newer, stronger hashing
      algorithms are supported.
     </p>
     <p class="para">
      It is worth noting that over time this constant can (and likely will)
      change. Therefore you should be aware that the length of the resulting
      hash can change. Therefore, if you use <strong><code>PASSWORD_DEFAULT</code></strong>
      you should store the resulting hash in a way that can store more than 60
      characters (255 is the recomended width).
     </p>
     <p class="para">
      Values for this constant:
     </p>
     <ul class="itemizedlist">
      <li class="listitem">
       <span class="simpara">
        PHP 5.5.0 - <strong><code>PASSWORD_BCRYPT</code></strong>
       </span>
      </li>
     </ul>
    </dd>

   
  </dl>

 </p>
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